Parts Department

Braking Faults

Common Brake faults

• Siezed Caliper Pistons become stuck in the caliper and refuse to back off when brake pedal released. Causes premeature wear of the discs and pads and when advanced, overheating of the brakes.
• JUDDER -
  Symptoms: Front - Vibration and wobbling of the steering wheel when braking.
  Symptoms: Rear - Vibration felt through the floor of the car.
  Cause: Usually driver error -
  1) Holding the footbrake down when car is stationary. This causes the brake pad to be in contact with the brake disc on one position on the disc causing the heat to be retained in the disc at this point . The rest of the disc can cool and contract but the area in contact with the pads does not contract and this warps the disc.
  2) Another problem with holding your foot on the pedal when stationary is that the brake pad can stick to the hot disc resulting in transferrence of pad material to the disc. As this pad material stuck onto the disc passed the brake pad next time you brake the pad snatches at the disc.
  3) Overheating the brakes causes hot spots on the discs. These hot spots have a different amount of friction when passing the pads.
  
• Pulsing - Disc thickness variation. Where the discs have worn unevenly due to caliper problems or wheel bearing or flange problems causing rotor run out.
• FADE - Symptoms - After very heavy braking the brakes are pressed but has little or no effect. Cause - Brakes have become very hot and the pad material becomes less effective. Also when the pad becomes hot it produces a gas which can build up between the brake pad and the brake discs which forces the pad away from the disc.
• NO PEDAL - Symptoms: After hard braking the pedal travels to the floor but no braking effect. Cause: Boiled brake fluid. When the brakes get very hot the brake fluid can boil and turn into a gas. When pressing the brake pedal all that happens it the gas becomes compressed instead of transferring the pressure to the brakes.
• SOFT PEDAL - Symptoms: Pedal feels soft like treading on a spong. Cause: Air in brake fluid or expanding brake hose (see also NO PEDAL)..

Common Driver faults are:

• RIDING - Holding the footbrake down when car is stationary. This causes the brake pad to be in contact with the brake disc on one position on the disc. If the disc is warm/hot the disc cools unevenly which can cause warping, the disc can develop a 'hot spot' where the pad is in contact, the pad can transfer a small amount of pad material onto the disc. One or all of these can cause 'judder' (see above). USE YOUR HANDBRAKE!
• Not allowing brakes to 'bed in'. New brakes should be used with caustion without excessive demands being made on them for a few hundred miles until the surface of the pad has worn away and the pad and disc have mated together. Brake discs should be heated up gradually by light to medium braking on a clear road during this time and then allowed to cool whilst still driving. Full brake efficiency will not be noticed until after bedding in. Also excessive heating of a new disc can result in warping.

THE ABOVE BAD DRIVING HABITS MAY DAMAGE YOUR BRAKES!